AUTHOR=Ito Shoki , Iwazumi Kaori , Sukigara Haruna , Osanai Takashi 

TITLE=Fumarase From Cyanidioschyzon merolae Stably Shows High Catalytic Activity for Fumarate Hydration Under High Temperature Conditions

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.560894

DOI=10.3389/fmicb.2020.560894

ISSN=1664-302X

ABSTRACT=<p>Fumarases (Fums) catalyze the reversible reaction converting fumarate to <sc>l</sc>-malate. There are two kinds of Fums: Class І and ІІ. Thermostable Class ІІ Fums, from mesophilic microorganisms, are utilized for industrial <sc>l</sc>-malate production. However, the low thermostability of these Fums is a limitation in industrial <sc>l</sc>-malate production. Therefore, an alternative Class ІІ Fum that shows high activity and thermostability is required to overcome this drawback. Thermophilic microalgae and cyanobacteria can use carbon dioxide as a carbon source and are easy to cultivate. Among them, <italic>Cyanidioschyzon merolae</italic> and <italic>Thermosynechococcus elongatus</italic> are model organisms to study cell biology and structural biology, respectively. We biochemically analyzed Class ІІ Fums from <italic>C. merolae</italic> (<italic>Cm</italic>FUM) and <italic>T. elongatus</italic> (<italic>Te</italic>Fum). Both <italic>Cm</italic>FUM and <italic>Te</italic>Fum preferentially catalyzed fumarate hydration. The catalytic activity of <italic>Cm</italic>FUM for fumarate hydration in the optimum conditions (52°C and pH 7.5) is higher compared to those of Class ІІ Fums from other organisms and <italic>Te</italic>Fum. Thermostability tests of <italic>Cm</italic>FUM revealed that <italic>Cm</italic>FUM showed higher thermostability than those of Class ІІ Fums from other microorganisms. The yield of <sc>l</sc>-malate obtained from fumarate hydration catalyzed by <italic>Cm</italic>FUM was 75–81%. In summary, <italic>Cm</italic>Fum has suitable properties for efficient <sc>l</sc>-malate production.</p>